1. Field of the Invention
Embodiments of the present invention generally relate to lubricants. More particularly, embodiments relate to lubricants disposed over magnetic storage media, such as rotatable thin film magnetic discs.
2. Description of the Related Art
Information storage systems, such as disk drive memory systems, have been used in computers and other data processing devices for many years for storage of digital information. Typically, information is recorded on concentric memory tracks of a rigid magnetic storage medium, such as a disc, the actual information being stored in the form of magnetic transitions within the medium. The disc Is typically comprised of a thin rigid substrate, an underlayer, a magnetic layer, and a protective overcoat. The discs are rotatably mounted on a spindle, the information being accessed by means of transducers located on a pivoting arm which moves radially over the surface of the disc. The read/write heads or transducers must be accurately aligned with the storage tracks on the disc to ensure proper reading and writing of Information.
In the operation of typical disk drives, the read/write head slides against the surface of the disc as the disc starts to rotate. Upon reaching a predetermined rotational speed, the head floats in air at a predetermined distance from the surface of the disc where the head is maintained during reading and recording operations. The read/write head floats very close to the surface of the disc during movement to maximize the signal quality. Due to the spacing closeness, the head can make intermittent contact with the disc surface. The head also slides on the disc as the disc rotation stops.
To reduce the wear and material interaction on the surface of the disc, the disc further includes a lubricant topcoat typically applied over the protective overcoat. The lubricant is intended to reduce the wear of the interface between the read-write head and the disc, especially during start/stop cycles in which the head is in contact with the disc. The lubricant system typically comprises a mixture of a perfluoropolyether, such as “FOMBLIN® Z-DOL” available from Ausimont USA, a subsidiary of Montedison S.P.A. of Milan, Italy, and a catalytic blocking agent, such as the hexaphenoxy compound “X-1P” available from The Dow Chemical Company of Midland, Mich. The perfluoropolyether provides lubrication of the disc while the catalytic blocking agent prevents catalytic decomposition of the perfluoropolyether. It is believed that the catalytic blocking agent prevents exposed metal sites of the head or of the disc from reacting with the perfluoropolyether.
One problem with the lubricant system Including a mixture of a lubricant compound, such as a perfluoropolyether, and a catalytic blocking agent, such as a hexaphenoxy compound, is that the catalytic blocking agent may be immiscible with the lubricant compound and may form droplets of the catalytic blocking agent on the lubricant compound. This “phase separation” between the lubricant compound and the catalytic blocking agent may cause reduced protection of the lubricant compound by the catalytic blocking agent. Moreover, the droplets of the catalytic blocking agent at the surface of the disc may perturb the head during operation of the disk drive, thus, causing the head to improperly read or write to the disc.
Therefore, there is a continuing need for an improved lubricant system to be used with magnetic storage media.